Question

Plants consume--- to make their own food.
(A) oxygen
(B) carbon dioxide
(C) Both A and B
(D) None of these

Answer 1

The living things which make their own food by consuming carbon dioxide, water, chemicals and sunlight are known as autotrophs. Plants are also autotroph species. Plants convert light energy into chemical energy with the help of photosynthesis process.

Complete step by step answer:
Autotrophs: An autotroph is an organism which produces its own food by consuming carbon dioxide, water, light and minerals. Autotrophs are also known as producers because they produce their own food.
Examples of autotrophs are as follows:
Plants, Algae and some type of bacteria.
A plant is a living thing which has leaves, stem and roots as its body parts. Plants are considered as autotrophs as they produce their own food. The process used by the plants for the production of food is known as photosynthesis.
Photosynthesis: The process used by the plants to convert light energy into chemical energy is known as photosynthesis. Carbon dioxide, water, light and chlorophyll are the inputs for the chemical reaction of photosynthesis. Glucose, water and oxygen are outputs of photosynthesis process.
Reaction of the photosynthesis process is as follows:
${\text{C}}{{\text{O}}_{\text{2}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}\xrightarrow[{chlorophyll}]{{sunlight}}{{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}} + {{\text{O}}_{\text{2}}} \uparrow$
So from the above reaction we can conclude that plants consume carbon dioxide to make their own food.
Hence option (B) is correct.

Note:
As we can see that photosynthesis process proceeds with the help of a reaction but in actual, reactions happen in two stages. First stage consists of light capturing chemical reactions while in the second stage enzyme controlled reactions are performed.